chris@MIMSY.UMD.EDU (Chris Torek) (07/21/89)
In article <77962@pyramid.pyramid.com> Carl S. Gutekunst writes: >The MIServer uses a RAM catridge -- a technology unavailable in 1985 -- >mostly because some customers complained about the floppies. Not because >the floppy didn't work, or wasn't reliable, but because they were >squeemish about doing IMPL from a floppy. Actually, the floppies did have one problem. Those of you in areas without thunderstorms (read: California :-) ) would never notice, of course. Century Data Systems made the same mistake with their T300, only worse. You see, the floppies are used to record machine check information. A power failure---especially the sort that has the line voltage ring first---will often cause a machine check. When lightning strikes nearby, making the power jitter and then fail, Pyramids have a habit of starting to write a machine check record while the floppy is getting confused by the fading power. Sometimes the floppy will scribble over the microcode. We went through several floppies each summer this way. Chris